<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src="https://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script>
    <title>Document</title>
</head>
<body>
    <div>
        <p>1</p>
        <p>2</p>
        <p>3</p>
    </div>
    <script>
        console.log(document.querySelector('div').children);
        console.log($("div").children());
        $("div").children().text("测试")
        $("div p:first").text("hello")
    </script>
</body>
</html>